Production of colored photographic images



Patented Sept. 10, 1940 UNITED STATES PRODUCTION OF COLORED PHOTO- GRAPHIG IMAGES John David Kendall and Ronald Bernard Collins, Hford, England, assignors to Ilford Limited, Ilford, Essex, England, a British company No Drawing. Application April 4,1939, Serial No. 265,998. In Great Britain April 8, 1938 16 Claims.

The invention relates to the production of colored photographic images by color development. It is known that a colored image may be formed simultaneously with the silver image obtained by developing an e posed silver halide emulsion in the presence of a substance known as a color former, for example, if the color former is mixed with the developer or the emulsion. The colored image thus produced may be revealed by m dissolving out the silver image with the aid of Farmers Reducer or other known suitable silver solvents.

It is an object of this invention to provide a new range of color formers. A further object of the invention is to provide a method of producing colored photographic images with the aid of such color formers and a still further object is to provide light sensitive silver halide photographic materials containing the new color formers. 7

Other objects of the invention will appear hereinafter.

According to the present invention colored photographic images are produced by developev ing silver halide photographic emulsions, in which a latent image has been formed, with an aromatic amino compound as the developer, in the presence of a color form-er which is the condensation product of one molecule of an aldehyde or ketone with one molecule of a pyrazole--one which has a reactive methylene group in the 4-pos'ition and in which the 1 and 3 positions may or may not be substituted.

The pyrazole-5 ones may be represented by 35 the following general formula:

in which R1 and R2 'may be the same or differ- 45 ent and each represent a hydrogen atom, a hydrocarbon radical, e. g., an alkyl, aryl, aralkyl, substituted alkyl, substituted aryl or substituted aralkyl group or a heterocyclic group. Thus, for example, R1 or R2 may be a'methyl, ethyl, 5o propyl or higher alkyl group a carbmethoxy or higher carbalkoxy group, a phenyl or naphthyl group, a benzyl or phenyl-ethyl group, or afuryl, coumaryl, thienyl or benzthiazolyl group and such groups may be substituted by other atoms 55 or groups e. g., chlorine or bromine atoms, nitro groups, hydroxy, methoxy and other alkoxy groups, carbethoxy and other carbalkoxy groups and carbalkoxyalkyl groups. Thus, for instance,

Rror R: may be, instead of a. phenyl group, a

60 p-nitrophenyl group, a 2:4-dinitrophenyl group,

a hydroxyphenyl group, a chlorphenyl group or a dichlorphenyl group. g The aldehyde or ketone employed may be represented by the following general formula:

in which R3 and R4 may be the same or different and each represent a hydrogen atom or a hydrocarbon radical, e. g., alkyl, cycloalkyl, aryl, aralkyl, substituted alkyl, substituted aryl, substituted aralkyl or R3 and R4 may together form part of a carbocyclic or heterocyclic group.

Examples of suitable aldehydes'are formaldehyde, benzaldchyde, phenylacetaldehyde, salicylaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, furfuraldehyde, N-dimethylaminobenzaldehyde and cinnamic aldehyde, and examples of suitable ketones are acetone, acetophenone, benzophenone, cyclopentanone, acetoacetic ester and m'ethyl-p-naphthyl ketone.

The nature of the condensation product varies with the conditions of the reaction, and the relative proportions of the reactants. One molecule of the pyrazole 5-one reacts with one molecule of the aldehyde'or ketone to give products represented by the following general formula:

nary temperatures in the presence of a condensing agent such as piperidine or hydrochloric acid, but is preferably carried out at higher,

temperatures, e. g., 40 to 200 C. and preferably 14 0 to 180 C.

' The reaction product chiefly consists of a compound represented by Formula! but there is a probability of small amounts of a compound represented by the following formula being formed in admixture therewith: 7 I

wherein R1, R2, R3 and R4 have the same significance as in Formula. I. I

The presence of minor amounts of a symmetrical compound of Formula II is immaterial, since it has been found that both types of compound, or mixtures of them, function satisfactorily as color formers. The unsymmetrical compounds may be purified so that they are free from symmetrical compounds.

Simple pyrazolones have been previously employed as color formers, but sufier from the dis.- advantages of their appreciable solubility in developing solutions and their tendency to difluse from one emulsion layer to another, when incorporated in emulsion layers of photographic multi-layered material. The compounds of the present invention are much less soluble and are much more substantive towards gelatine, so that they possess a greatly reduced tendency to diffuse out of an emulsion layer.

The color formers may be employed in two different waysf Thus they may be incorporated in the silver halide emulsion which is to be developed or they may be added to the developer solution. In either case, the result on development is to yield images in shades ranging from magenta to mauve. V

Suitable aromatic amino compounds which may be employed as the developers in conjunction with the color-formers of this invention are derivatives of p-phenylene diamine and particularly of the asymmetric dialkyl p-phenylenediamines, e. g., p-aminodimethylaniline, paminodiethylaniline and p-aminodibutylaniline. Other developing agents which may be used include p-phenylenediamine itself,- p-methylaminoaniline, p-ethylaminoaniline and p-aminophe n01, N.N-diethyl-o-phenylenediamine, chloro-pphenylenediamine, 1.2.5.-toluylenediamine, 2- amino-5-diethylaminotoluene, N-p-aminophenylpiperidine, N-methyl-N-hydroxyethyl-p-phenylenediamine, N-butyl-N-hydroxyethyl-p-phenylenediamine, 2-amino-5-hydroxyethyl-butyl aminotoluene and its dihydrochloride and a-w-dihydroxypropyl-p-phenylene diamine. These aromatic amino-developing agents may be used in the form of their salts, which may be either inorganic or organic. The salts are in general more stable than the free bases. As examples of suitable salts mention is made of the hydrochlorides, sulfates and acetates.

In the succeeding examples, the following solution is given by way of example as illustrating the natureof developing solutions which may be employed embodying a color former in accordance with the invention.

Developing Solution A Diethyl-p-phenylenediaminehydrov chloride gm 1 Sodium carbonate (crystals) NazCoal0H2O gms Sodium sulphite (crystals) NazSOs'THzO gmS 12.5

Color former solution (1% or saturated solution, whichever is weaker) ccs Water to make litre 1 method of production of the new colorformers, and their use:

Example 1 1.74 gms. of 1-phenyl-3-methyl-S-pyrazolone and 1.06 gms. of benzaldehyde were heated together on an oil-bath at C. for about one hour. A red oil was produced which was cooled and dissolved in 10 ccs. of warm alcohol, from which 1.93 gms. of a red crystalline solid deposited on cooling. This solid was crystallised from a further 15 ccs. of alcohol yielding 1.3 gms. of red crystals melting at 106-107 C. Developing Solution A, when including this compound and used for the development of photographic silver halide images, produced a magenta image together with the silver image.

Example 2 l-pheny1-3-methyl-4' paradimethylaminobenzal-fi-pyrazolone 4.35 gms. of 1-phenyl-3-methyl-5-pyrazolone, 3.74 gms. of p-dimethylaminobenzaldehyde, 30 cos. of glacial acetic acid and 10 ccs. of 'dry alcohol were mixed together and the mixture boiled gently under a reflux condenser on a water bath for about one and a quarter hours. The solution first became red and later crystals were deposited. The mixture was cooled, filtered and the solid residue was washed with acetic acid, alcohol and water and then dried. The solid was then purified by boiling successively with three 250 ccs. lots of methyl alcohol and filtering oft, leaving 4.06 gms. of shining red crystals melting at 197 C.

Developing Solution A when including this compound and used for the development of silver halide photographic emulsions produced a weak magenta image together with the silver image, the weakness of the image being due to the insolubility of the compound in ethyl alcohol and the developer solution.

Example 3 1-phenyl-3-methyl-4-phenyl methyl methylene-5-pyrazolone CcH a 1.74 gms. of 1-phenyl-3-methyl-5-pyrazolone, 1.20 gms. of acetophenone, 10 cos. of glacial acetic acid and 3.5 cos. of dry alcohol were heated on a water bath for two hours and then boiled gently under a reflux condenser for a further hour. A yellow crystalline solid was formed which was filtered ofi and washed and recrystallised from 20 cos. of alcohol yielding 0.23 gm. of small deep yellow crystals melting at 87 C.

Developing Solution A when including this substance and used for the development of silver halide photographic emulsions produced a deep violet image, together with the silver image.

Example 4 1.74 gms. l-phenyl-3-methyl-5-pyrazolone and 1.74 gms. phenylacetaldehyde were heated in an oil bath at 160 C. for 3 hours. The residual oil was extracted with benzene and ethyl alcohol separately leaving a brown solid. This was recrystallised from benzene with addition of petroleum ether to induce crystallisation giving 1-2 gms. of a solid which melted at 101-103 C.

Developing Solution A when including this compound and used for the development of silver halide emulsions produced a mauve image in addition to the silver image.

1.65 gms. m-nitro-acetophenone and 1.74 gms. 1-phenyl-3-methyl-5-pyrazolone were heated in an oil bath at 160 C. for 3 hours. The melt set to a pale yellow solid which was extracted with cos. ethyl alcohol; the addition of water to the alcoholic extract caused the precipitation of a yellow oily solid which melted at 150-160 C.

Developing Solution A when including this compound and used for the development of silver halide emulsions produced a magenta image in addition to the silver image.

In each of the above examples, the dye image may be revealed by bleaching out the silver image with, for example, Farmers Reducer or other known photographic bleaching agent.

In addition to the specific pyrazolone colorformer described in the foregoing examples the following are examples of color-formers according to this invention:-- 1-phenyl-3-methyl-4- (m hydroxybenzal) -5-pyrazolone l-phenyl3-methyl-4- (p-hydroxybenzal) -5-pyrazolone 1-phenyl-3-methyl-4- (o-hydroxybenzal) -5-pyra- 1 phenyl 3 methyl 4 (carbethoxy methyl methyl-methylene) -5-pyrazolone 1-phenyl-3-methy1 4 (2(1hydroxy) naphthyl methyl methylene) -5-pyrazolone 1-phenyl-3-methyl -'-4- diphenylmethylene-S-pyrazolone j 1-phenyl-3-methyl -4- (m'ethyl-w-styryl methylene) -5-pyrazolone 1-phenyl-3-methyl-4-cyclopentanyl-fi pyrazolone l-phenyl 3 methyl-4- (methyl p-methylphenyl methylene) -5-pyr'azolone Example 6 This example illustrates the incorporation of the color formers of this invention in emulsion layers 20 cos. of 1% solution in ethylene glycol mono-methyl ether of 1-phenyl-3-methyl-4-benzal-5-pyrazolone were added to cos. of 10% aqueous solution of gelatin and the mixture added to cos. of a melted photographic Gaslight emulsion containing approximately 20 gms. of silver halide, principally silver chloride, per pound weight of emulsion. The emulsion thus prepared was coated on a paper support and dried. The emulsion coated paper was exposed under a negative and was then developed with a developing solution of the constitution of developing Solution A excluding the color former but including an equivalent quantity of the water miscible liquid such as ethyl alcohol or ethylene glycol mono methyl ether. A magenta image was produced together with the silver image.

The compounds:

1-phenyl-3-methyl-4-paradimethyl aminobenzal- 5-pyrazolone v 1-phenyl-3-methyl -4- phenylmethylmethylene-5- pyrazolone 1-phenyl-3-methyl-4-phenylethylidene-5-pyrazolone 1-phenyl-3-methyl-4-m-nitrophenylmethylmethylene-fi-pyrazolone Y may be employed in a similar way in place of the 1-phenyl-3-methyl-4-benzal-5-pyrazolone referred to above.

The process of development employing the color formers in accordance with the present inven tion may be applied either to a latent image in an emulsion of a silver halide which has been exv able silver salt by means of known photographic bleaching agents. In the last two cases the residual silver halide and the silver salt respectively may be made developable by the action of light or in any other way, e. g., by treatment with sodium arsenite.

We claim:

1. A photographic color forming developer which comprises an aromatic amino developing compound and the condensation product of one;

molecule of a pyrazole-5-one having a reactive methylene group in the 4-position and one molecule of a compound selected from the group consisting of aldehydes and ketones.

2. A photographic color forming developer which comprises an aromatic amino developing in which R1, R2, R3 and R4 represent radicals taken from the group consisting of hydrogen,

hydrocarbon and heterocyclic radicals.

3. A photographic color forming developer which comprises an asymmetrical di-alkyl p phenyle ne diamine and the condensation product of one molecule of a pyrazole-S-one having a reactive methylene group in the 4-position and one molecule of a compound selected from the group consisting of aldehydes and ketones.

4. A method of producing a colored image in a silver halide emulsion in which a latent image has been formed, which comprises developing the emulsion with an aromatic amino developing compound in the presence of the condensation product of one molecule of a pyrazole-S-one having a reactive methylene group in the ii-position with one molecule of a compound selected from the group consisting of aldehydes and ketones.

5. A method of producing a colored image in a silver halide emulsion in which a silver image has been produced and the residual silver halide removed by fixing, which comprises converting the silverimage to a redevelopable silver salt by known photographic means and re-developing with an aromatic amino compound in the presence of the condensation product of one molecule of a pyrazole-s-one and one molecule of a compound selected froni the group consisting of aldehydes and ketones.

6. A light sensitive silver halide photographic emulsion containing a color former which is the condensation product of one molecule of a pyrazole--one having a reactive methylene group in the 4-position with one molecule of a compound selected from the group consisting of aldehydes and ketones.

7. A light sensitive silver halide photographic emulsion containing a color former which is a compound of the general formula:

in which R1, R2, R3 and R4 represent radicals taken from the group consisting of hydrogen, hydrocarbon and heterocyclic radicals.

8. A process as set forth in claim 4 wherein the condensation product is 1-phenyl-3-methyl-4- benzal-5-pyrazolone.

9. A process as set forth in claim 4 wherein the condensation product is 1-phenyl-3-methy1- 4-phenyl-methyl-methylene-5-pyrazolone.

10. A process as set forth in claim 4 wherein the condensation product is 1-phenyl-4-phenylmethyl-methylene-5-pyrazolone.

11. A light sensitive silver halide photographic emulsion containing as a color former l-phenyl- 3-methyl-4-benzal-5-pyrazolone.

12. A light sensitive silver halide photographic emulsion containing as a color former l-phenyli3-methyl-i-phenyl-methyl-methylene-5-pyrazo one.

13. A light sensitive silver halide photographic emulsion containing as a color former l-phenyli-phenyl-methyl-methylene-5-pyrazolone.

14. A developer as set forth in claim 3 wherein the condensation product is 1-pheny1-3-methyl- 4-benzal-5-pyrazolone.

15. A developer as set forth in claim 3 wherein the condensation product is 1-phenyl-3-niethyl- 4-phenyl-methyl-methylene-5-pyrazolone.

16. A developer as set forth in claim 3 wherein the condensation product is l-phenyl-i-phenylmethyl-methylen-5-pyrazolone.

JOHN DAVID KENDALL. RONALD BERNARD COLLINS.

- CERTIFICATE OF'CORRECTION. Patent No. 2,215,986. September 10, 191w.

I JOHN DAVID K NDA L, ET AL.. I .It is hereby certified that error appears in theprinted specification of theabove numbered patent requiring correction as follows: Page 5, second column, line 12, begirming with "Example 6" strike out all to and including the word and period "aboveJ" in line 145, and insert the same on same page 5, first column, after thenparagraph ending with the words silver image"; in line 1;]; and that the said Letters .Patent h l he read with this correction therein that the same maj conform to the record of the case in the Patent Office.

Signed and sealed this 22nd day of October, A. D. 1911.0.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents. 

